engleski

Affinity labeling of the membrane protein-binding component of human polymorphonuclear leukocyte receptors for leukotriene B41

A radiolabeled N-(3-aminopropyl)-leukotriene B4 amide ([H-3]LTB4-APA) analog of the potent leukocyte chemotactic factor leukotriene B4 (LTB4) binds to receptors for LTB4 in plasma membrane-enriched preparations from human blood polymorphonuclear leukocytes (PMNL) and intact PMNL with respective mean dissociation constants of 2.3 nM and 69 nM at 4-degrees-C. The [H-3]LTB4-APA bound to plasma membrane-enriched preparations from PMNL was covalently cross-linked to membrane proteins with disuccinimidyl suberate. Solubilization and resolution by SDS-PAGE of proteins from [H-3]LTB4-APA-labeled PMNL membranes revealed predominant labeling of a 60-kDa protein. Labeling of the PMNL membrane protein was inhibited by LTB4 and its analogs at concentrations similar to those inhibiting the binding of [H-3]LTB4 to its receptor, with an identical rank order of potency of LTB4 > 20-hydroxy-LTB4 > LTB4-APA = 5(S), 12(R)-dihydroxy-eicosa-14-cis-6, 8, 10-trans-tetraenoic acid >> LTD4 = LTC4. GTP suppressed the labeling of the 60-kDa PMNL membrane protein to an extent consistent with the decrease in receptor affinity for LTB4 induced by GTP. The stereospecificity of the affinity cross-linking reaction and the regulation by GTP support the identification of an approximately 60-kDa protein as the binding component of the PMNL receptor for LTB4.

receptors ; leukotriene ; polymorphonuclear leukocyte

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